<template>
  <!-- 添加一个标志ref，方便选择 -->
  <div class="area" ref="area_scroll" >

    <div class="scroll_wrap" v-if="cityInfo">

      <div class="hot_wrap">
        <div class="title citylist">热门城市</div>
        <ul class="hot_city">
          <li v-for="(item,index) in cityInfo.hotCities" :key="index" @click="$emit('selectCity',item)">
            {{item.name}}
          </li>
        </ul>
      </div>

      <!-- 所有城市 -->
      <div class="city_wrap">
        <!-- 先遍历显示字母再显示字母包含的城市 -->
        <div class="city_content citylist" v-for="(item,index) in keys" :key="index">
          <!-- 根据字母key展示城市名 -->
          <div class="title">{{item}}</div>
          <ul>
            <li v-for="(city,index) in cityInfo[item]" :key="index" @click="$emit('selectCity',city)">
                {{city.name}}
            </li>
          </ul>

        </div>

      </div>
    </div>

    <div class="area_keys">
      <ul>
        <li @click="selectKey(0)">#</li>
        <li  @click="selectKey(index+1)" v-for="(item,index) in keys" :key="index">
          {{item}}
        </li>
      </ul>
    </div>
    
  </div>
</template>

<script>
import BScroll from 'better-scroll'
//引入scroll插件

export default {

  name: "Alphabet",
  data(){
    return{
      scroll:null
    }
  },
  props:{
    cityInfo:Object,
    keys:Array,

  },
  methods:{
    //实例化scroll插件
    initScroll(){
      this.scroll = new BScroll(this.$refs.area_scroll,{
        click:true //设置可以实现被点击
      });
    },
    selectKey(index){
      // console.log(index);
      // console.log(this.$refs.area_scroll.getElementsByClassName('citylist'));
      const citylist = this.$refs.area_scroll.getElementsByClassName('citylist');
      // 根据下标,滚动到相对应的元素上
      let element= citylist[index];

      //滚动到对应的位置上，用scroll模块对象
      this.scroll.scrollToElement(element,200);


      // console.log(this.$refs.area_scroll.getElementsByClassName("citylist"));
      // const citylist = this.$refs.area_scroll.getElementsByClassName(
      //   "citylist"
      // );
      // // 根据下标,滚动到相对应的元素上
      // let el = citylist[index];

      // // 滚动到对应的位置上
      // this.scroll.scrollToElement(el, 250);
    }
  }

};
</script>
<style scoped>
.area {
  margin-top: 10px;
  box-sizing: border-box;
  padding: 0 16px;
  background: #fff;
  height: calc(100% - 65px);
  overflow: hidden;
}
.scroll_wrap {
  background: #fff;
  overflow: auto;
}
.title {
  color: #aaa;
  padding: 15px 0;
}
.hot_city {
  padding: 0 16px;
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
}
.hot_city li {
  width: 30%;
  background: #f1f1f1;
  margin: 0 10px 10px 0;
  text-align: center;
  padding: 10px;
  box-sizing: border-box;
}
.city_content li {
  padding: 10px;
  border-bottom: 1px solid #eee;
}
.area_keys {
  position: fixed;
  right: 0;
  top: 25%;
  color: #aaa;
  font-size: 12px;
  line-height: 1.4;
  text-align: center;
  padding: 0 5px;
}
</style>
